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microbiology > lec 3 > Flashcards

lec 3 Flashcards

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Biology 101 flashcards
1
Q

cell shapes of prokaryotes

A

1) coccus: basically a sphere
2) rods
3) spirillium: twisted rods
4) spirochete: very good at swimming through liquid and drill into tissues
5) stalk: more complex, their membranes are capable of elongating and creating motile daughter cells. mostly water bond and capable of attaching to water molecules
6) filamentous: forms a very long filaments and the cells that does detach from each other

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2
Q

functions of the cell wall of bacteria

A
  • allows the bacteria to withstand the intracellular osmotic pressure
  • shape and rigidity
  • on top of the cytoplasmic membrane
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3
Q

gram stain

A

a procedure to stain cells in order to view them under the microscope

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4
Q

cells are divided into gram stains based on their:

A

cell wall composition

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5
Q

how to make a gram stain

A

1) prepare a thin later of bacteria o na slide
2) mix with crystal violet for 1 min –> purple
3) add iodine for 1 min –> purple
4) decolonize with alcohol for 20 sec –> gram +: purple, gram - : color less
5) counterstain with safranin fro 1-2 min –> gram +: purple, gram -: pink to red

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6
Q

gram positive vs gram negative

A

gram negative has an outer membrane on top of the peptidoglycan

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7
Q

structure of peptidoglycan

A
  • the backbone is basically similar among most
  • 2 sugars: N-acetylglucosamine and N-acetylmuramic acid
  • side chain attached to the sugars: peptide chain –> D amino acids
  • mammals destroys these bacteria by producing lysozyme and breaking the beta 1-4 linkages
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8
Q

gram — is more sensitive to lysozyme, why?

A

positive, its peptidoglycan is exposed

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9
Q

transpeptidation

A

polymerization of the sugar backbones that provides rigidity in only one direction

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10
Q

transpeptidation in gram neg

A

direct cross linkage (covalently)

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11
Q

transpeptidation in gram positive

A

inter bridge cross linkage, by adding more AAs between the 2 sugars, so then you make it thicker

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12
Q

how does penicillin destroy bacterial infections

A

inhibits binding the 2 peptide chains together by inhibition transpeptidase enzymes

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13
Q

upto —- % of the cell wall is peptidoglycan

A

90

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14
Q

proteins attached to the peptidoglycan layer:

A

1) teichoic acid. *variable can be either or

2) lipoteichoic acid

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15
Q

how does TA and LTA impact the overall charge of the cell

A

net negative, because they are negative

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16
Q

what happen if LTA is bound to the peptidoglycan

A
  • it binds deeper with it and ends with a glycerol phospholipid
  • anchored inside the cytoplasmic memebtan
  • makes peptidoglycan fully attached to the cytoplasmic membrane
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17
Q

how are proteins attached to the peptidoglycan layer

A

enzyme: sortase

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18
Q

(T/F) eukaryotes doen have sortase

A

true

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19
Q

structure of the outer membrane of gram neg

A
  • porins
  • outer membrane proteins
  • inside layer: phospholipids
  • outer layer: LPS + phospholipids
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20
Q

periplasm space:

it is covered by:

A

where the peptidoglycan is located

- outer membrane and cytoplasmic membrane

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21
Q

function of LPS

A

protects the bacteria against antibiotics and host defence system

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22
Q

structure of LPS

A

a family of complex sugar polymers attached to lipid A

  • lipid A contains 6 lipid tails embedded in the membrane
  • KDO links lipid A to the polysaccharide chain:
  • connected to core polysaccharides (don’t change much)
  • and O specific polysaccharides or O antigens:repeating sequences of 2-4 monosaccharides (very variable)
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23
Q

consequences of lipid A

A

septic shock

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24
Q

pseudomuerin in archaea vs. peptidoglycan

A
  • lack D AAs, instead has L AAs
    contains N-acetylalsaminuronic aid instead of NAM
  • linkage is insensitive to lysozyme, due to its beta 1–> 3 linkage
25
Q

the great majority of archaea have — and/ or —- on their cell walls. some can be composed of —-

A

protein, glycoproteins, heteropolyasachchrides

26
Q

S layer

A

the cyrtslaline appearance of the cell walls of archaea
it may also be found in bacteria
gram + : on top of the peptidoglycan
gram -: on top of the outer membrane
- esp when the archaea is composed of any of: protein, glycoprotein, sugar

27
Q

the capsule or slime layer are composed of — for majority and —- in some gram positive

A

heteropolyasachcrides

homopolysaccharides

28
Q

how is the capsule attached to the cell

A

it is covalently bound to either the outer membrane or the peptidoglycan layer

29
Q

fxn of capsule

A

doesn’t confer sig strength

- due to its glue like texture, external matter stick to it therefore, protection against the host defence system

30
Q

flagella and fimbriae are —- than the size of the bacteria

A

larger

31
Q

function of fimbriae

A

used for attachments and anchor the cell to something. these are short filaments o the surface of the bacteria

32
Q

monotrichous vs. peritirichous vs. lophotrichous

A

diagrams

33
Q

structure of flagella

A

diagrams

34
Q

fimbriae is found primarily on gram — bacteria

A

negative

35
Q

movement in peritrichous

A

forward + change direction

36
Q

movement in mono and lopho

A

forward and reverse

37
Q

how is fimbriae attached to gram positive

A

via sortase on the peptidoglycan

38
Q

assembly of fimbriae for both gram neg and pos

A

diagram

39
Q

taxis

A

directed movement toward or away from a gradient of chemical or physical agents
- when there is an attractant, the bacteria keeps moving in the right direction. so it spends more time in the direction that is favoured

40
Q

name the surface appendages of bacteria and archaea

A

flagella, fimbriae

41
Q

what is an endospore

A

highly differentiated cells that are extremely resistant to harsh environments
- safety vessel for the genome of a species

42
Q

2 bacterias that are well known for producing endospore

A

clostridium, bacillus

43
Q

structure of and endospore (outer most layer to the inner most)

A

1) exosporium
2) spore coat
3) core wall
4) cortex
5) DNA

44
Q

exosporium

A

a coat of protein on top of the spore

45
Q

spore coat

A

layers of protein that are only found in the spores of the species (spore specific protein)

46
Q

core wall

A

contains some protein and genome of the species of interest

47
Q

cortex

A

on top of the core wall, thick layer of peptidoglycan

48
Q

in the core of an endospore, besides the genome and proteins you also have:

A

1) SASPS

2) Dipicolnic acid (DPA) + Ca2+

49
Q

SASPS

A

bind to the DNA an =d protect it from bad things ,esp UV light

50
Q

DPA + Ca2+

A

they dehydrate the core in order to stop enzymatic activity therefore, keep the spore fresh

51
Q

vegetative cycle

A

where the bacteria is actively growing and dividing

52
Q

sporulation

A

when the env becomes harsh a spore is formed

53
Q

during germination —– is increased, resulting in —-

A

water uptake, outgrowth

54
Q

cell inclusions

A

in bacteria and archaea, nrg reserves and building blocks are sometimes stored in granules or inclusions

55
Q

cell inclusions are often enclosed by

A

a single layer of phospholipid, protein, glycoprotein

56
Q

what nutrients are stored in cell inclusions

A

P,S,C

57
Q

How are some bacteria able to respond to earth’s magnetic field

A

their cell inclusions store magnetites, and allows the cells to respond to magnetic fields
- meganotaxis

58
Q

how do cell inclusions confer buoyancy

A

when they store gas, the cell can float on the water and be closer to areas with a higher level of O2

microbiology (9 decks)

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